1. Field of the Invention
The present invention provides a method of producing an oxide film by a metal organic chemical vapor deposition.
2. Related Art Statement
Single crystals of potassium lithium niobate and potassium lithium niobate-potassium lithium tantalate solid solution have attracted much attention as single crystals for a second harmonic generation (SHG) device generating a blue light used for a semiconductor laser. The single crystal mentioned above is capable of generating an ultraviolet ray. By utilizing such a short wave light, the single crystal mentioned above can thereby be applied in various fields such as optical disc memory, DVD laser light source, laser pointer, display, medical science, photo-chemistry and various kinds of light measurements. In addition, since the single crystal mentioned above has a large electro-optic effect, it can be applied for an optical memory device and so on utilizing its photorefractive effect.
On the other hand, a film-forming process by a metal organic chemical vapor deposition is disclosed in “Jpn. J. Appl. Phys.” Vol. 38, (1999) pages 5437 to 5441 and Japanese patent publication 8-73222A. According to the process, raw material gases for lithium and niobium and oxygen gas are mixed in a container and the thus mixed gas is then introduced into a reactor to proceed the chemical reaction in the reactor. A film of lithium niobate is thus deposited on a substrate in the reactor.
Further, according to “J. Crystal Growth” 148, (1995), pages 324 to 326, raw materials for lithium and niobium are mixed and the resulting mixed gas is then introduced into a reactor to form a film of lithium niobate.
Japanese patent 3, 253, 295 disclosed a method of producing an oxide superconductor by a metal organic chemical vapor deposition. According to the method, raw material gases for metal elements constituting the oxide superconductor are supplied into a reactor through the corresponding supply holes while each pressure of the gas is controlled. The raw material gases are mixed and reacted in the reactor.